Calling Multiple Actions at Once
To let each object start at the exact same frame, I suggest to send a message. Each of the objects can start whatever it should do when that message arrives. As they all get the same message at the same time you get a well synchronized animated scene.

This even works with non-actions, sequential operations and operations that do not start at the same time (but delayed).

The benefit is that you do not need to touch each single object when you want to change the activating event (e.g. changing from keyboard to mouse key). You simply change/add a single object that sends the message.